The present invention relates to a device for housing and manually controlling an electric relay for protection against overloads, of the thermal relay kind associated with a contactor.
It is usual to house electric switching apparatus protected against overloads and formed by the association of a contactor and a thermal relay in receptacles such as cases.
It is useful to recall that the contactor comprises a control electromagnet and determines the starting and stopping of a power load, for example a motor, as a function of the current which flows through the coil of the electromagnet. The thermal relay determines stopping of the motor, particularly in the case of an overload in at least one phase conductor of the motor : for this, the thermal relay comprises a switch which is controlled by an opening mechanism responsive to the deflection of bimetallic strips in the case of overloads and which is disposed electrically in series with the coil of the electromagnet of the contactor.
The opening mechanism must be re-set after each tripping procedure. Depending on the type of thermal relay considered, re-setting is either manual or automatic, or manual and automatic, including in this latter case a manual-automatic selection means. Manual re-setting takes place by means of a pusher disposed on the front face of the thermal relay.
In addition, it is often required in a thermal relay to be able to manually control stopping of the contactorthermal relay assembly by means of another pusher, also disposed on the front face of the thermal relay and acting on the opening mechanism for opening the switch.
When the contactor-thermal relay assembly is mounted in a case, a control push-button is provided on a front wall thereof. By pressing this button, an operator acts on the pushers for stopping and re-setting the thermal relay. This stopping and re-setting action is transmitted to the pushers of the thermal relay by transmission means whose role is to transform the movement of the control push-button into movement of the controlled pushers, while taking into account lost motion for application on the pushers and, on the other hand, staggering between the push-button and the pushers of the thermal relay.